If you check your filter and find oil on it, there's definitely some in the airbox too. The only way to inspect inside the air box on the Gen2 is to remove the gas tank and remove the air box covers. I wouldn't bother for this. The oil will drain down out of the air box drain tube. If there's any oil in the air box it will completely dry out within 6 months. If you wipe it out, fibers from the rag will catch on the rough cast interior of the air box. That's probably not a big problem either but I'd just leave it. Wiping won't do anything a little time won't do without the hassle of tearing the bike apart. The oil can't go down your intake, it would take a deep puddle in there to seep over the edges of the intake ducts. Any oil would be draining toward the back of the air box and going down drain tube. Six months from now, you won't have so much as a film of oil in there, it all dries up eventuall and there's no dust getting in there to collect in the oil so no problem.
'08 MIDNIGHT SAPPHIRE BLUE Now Deceased